Essay on Mct Q&a

1270 Words Jul 15th, 2013 6 Pages
(G) On Keypad & Sensor :
1. How many I/O interface pins between keypad (4x4) and PIC18f4520?
- Keypad (4x4) has 8 I/O interface pins.
- In this example schematic that has RB0 to R07 connected to the 8 I/O pins on to the Keypad (4x4)

- PIC18f4520 has 36 I/O pins that grouped into 5 ports
- It should require 8 pins to connect a 4x4 keypad.

2. How to detect if a key is depressed?
E.g. Of flowchart when things are input.
E.g. Of flowchart when things are input.
End

End

Wait for Key Release
Wait for Key Release
Swap I/O back to original setup
Swap I/O back to original setup
Combine ‘R’ and ‘T’ and put into global variable
Combine ‘R’ and ‘T’ and put into global variable
Read another input (Keypad) and put into
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4. What is the logic level sensed by PIC19f4520 when the touch sensor is pressed?

- V HL: High input logic level = 2.2 (Min)”OPT1, OPT2”
- V IL: Low input logic level = 0.8 (Max)”OPT1, OPT2”
Schematic Sensor

(H) Common Learning Issues
With 21 bits, a maximum of 2 MByte of program memory is addressable.
*Actual program memory is only 32-Kbytes this out of 2 MByte addressable space. This can store up to 16K of single word instructions.
With 21 bits, a maximum of 2 MByte of program memory is addressable.
*Actual program memory is only 32-Kbytes this out of 2 MByte addressable space. This can store up to 16K of single word instructions.
1- Number of I/O Ports on the PIC18f4529 and their names, number of pins.
Discovery:
36 I/O lines (pins) grouped into 5 ports
32K byte FLASH Program Memory
1536 x 8 On-chip Data Memory (RAM)
31-level stack
Parallel Slave port
Has a 21-bit Program Counter (PC)
36 I/Os
– All ports except RE3 can be used for digital I/Os
- RE3 is input only.
36 I/Os
– All ports except RE3 can be used for digital I/Os
- RE3 is input only.
PORT A: 8 pins (RA0 – RA7)
PORT B: 8 pins (RB0 – RB7)
PORT C: 8 pins (RC0 – RC7)
PORT D: 8 pins (RD0 – RD7)
PORT E: 4 pins (RE0 – RE3)
Each I/O PORT has 3 special function registers associated with it:
- the TRIS register – Data Direction (input or output)
- the PORT register – Read/Write DATA from or to I/O pin
- the LAT register

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